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The
tower is the key to the energy producing concept through the drawing
effect it creates to cause heated air to drive turbines to generate
energy. The efficiency of the tower (i.e. the conversion of heat
into kinetic energy) is determined by the difference between the
temperature in the collector and the temperature of the environment
at the top of the tower. A 1°C drop in temperature over every 100m
facilitates the necessary updraft effect from the tower. The
concept ensures effective operation even on cooler days, as it is
primarily dependent upon the temperature differential between the
air under the collector and air at the top of the tower.
The
relationship between the size and height of the tower directly
determines the power station’s efficiency. The tower needs to be as
tall as it is to provide an updraft sufficient to drive the turbines
to achieve proposed outputs. Greater cost efficiency is anticipated
from one tower as opposed to the several smaller towers with their
associated material and construction cost in relation to output
expectations. A 1000meter (3000+ feet) tall and 150 meters (450+
feet) diameter tower will provide preferred efficiency levels and
can be built using conventional construction techniques. A
television tower in Toronto, Canada is over 600 meters (1800+ feet)
high and serious plans are being made for 2000-meter (6000+ feet)
skyscrapers in earthquake-prone Japan.
The
tower is a simple hollow cylinder structure with a large diameter to
ensure stability from the relationship between the height to width
ratio.
Analysis of the lifespan of a reinforced concrete tower in a dry
climate is indicated at more than 50 years. Carbonization, the
usual reason for the deterioration of concrete, does not take place
in low humidity regions (Carbonization is the process that causes
concrete to lose its ability to protect its reinforced steel due to
the gradual conversion from the surface inwards of calcium hydroxide
in the cement into calcium carbonate as a result of the CO2
present in the atmosphere). This process is lessened in the absence
of excessive moisture. SolarMission and EnviroMission plan to build
Solar Towers in dry semi-arid and arid areas.
Temperature differentials produce an updraft velocity of about 15
meters per second and will allow maintenance crews to enter an
operating Solar Tower power station to undertake maintenance without
difficulty. This is a distinct advantage over other power stations
that need to be shut down during maintenance periods. Solar Towers
are designed to operate with very little down time.
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